I personally don't see it as a new Jak game. I see it as an abomination to all 3 series, even though I hate Sly Cooper, and I pray to Athena that this is non canon so I never have to touch it's filthy, disgustingness.
But yeah, I see it as a gimmick, a marketing ploy for the Move, another motion sensitive controller which I also hate. The only way I will even acknowledge this game, is if all 3 character's scenarios are independent and Jak, Sly and Ratchet never meet each other, and they are each in completely different universes.
If the story was canonical, then it would be the end of the series for me, I mean you can't have Jak meet Ratchet, and you most certainly can't have him meet Sly Cooper and vice versa. Like Jak, he's turned into some kind of badass dude, and then he'd meet Ratchet and... I don't know how it would work non-canonically let alone canonically.
I would be all for a non-canon Jak/Ratchet crossover, as long as it didn't have too big a story and was more a fun game-play orientated party game and that the next Jak game's story pretends that this Heroes on the Move plot didn't happen.